Isomerization of paraffin hydrocarbons

ABSTRACT

1. PROCESS FOR ISOMERIZING PARAFFINS BY MEANS OF SOLID ALUMINUM CHLORIDE CATALYST WHICH COMPRISES: (A) CONTACTING A PARAFFINIC FED SUBSTANTIALLY FREE OF UNSATURATED HYDROCARBONS AND HAVING AT LEAST FIVE CARBON ATOMS PER MOLECULE IN LIQUID PHASE WITH ALCL3 IN THE FORM OF PARTICULATE SOLID AT A TEMPERATURE IN THE RANGE OF -20 TO 130*C AND IN THE PRESENCE OF A MINOR AMOUNT OF SATURATED HALOHYDROCARBON PROMOTER IN WHICH THE HALOGEN IS CHLORIN OR BROMINE AND ALSO IN THE PRESENCE OF A SUPPRESSOR COMPRISING ADAMANTANOID HYDROCARBON SELECTED FROM THE GROUP CONSISTING ADAMANTANE, C11-C20 ALKYLADAMANTANES HAVING 1-3 ALKYL SUBSTITUTENTS, DIAMANTRANE AND C15-C24 MONOALKYLDIAMANTANE IN WHICH THE ALKYL SUBSTITUENT IS ATTACHED AT A BRIDGEHEAD POSITION THROUGH A PRIMARY CARBON ATOM SAID PROMOTER BEING CAPABLE OF INTERCHANGING SAID HALOGEN FOR A BRIDGEHEAD HYDROGEN OF SAID SUPPRESSOR; (B) CONTINUING SAID CONTACTING UNTIL SUBSTANTIAL ISOMERIZATION OF THE PARAFFINIC FEED HAS OCCURED; (C) AND RECOVERING A PARAFFINIC ISOMERIZATE FROM THE REACTION MIXTURE.

United States Patent Oflice Patented Oct. 1, 1974 US. Cl. 260---683.7622 Claims ABSTRACT OF THE DISCLOSURE Parafiins ranging from C to andincluding solid paraflins are isomerized by contacting the paraflinicfeed in liquid phase, preferably at 80 C., with powdered AlCl in thepresence of a minor amount of saturated halohydrocarbon promoter and inthe presence of an adamantanoid suppressor selected from adamantane,alkyladamantanes, diamantane and monoalkyldiamantanes. Theseadamantanoid suppressors have been found to be highly effective insuppressing undesirable side reactions while allowing the isomerizationreaction to proceed. Presence of the halohydrocarbon promoter in smallamount is essential. Additional benefits can be obtained by providing apartial pressure of H in the reaction zone and/ or from the presence ofHCl.

CROSS REFERENCE TO RELATED APPLICATION Copending application of AbrahamSchneider and Robert E. Moore, Ser. No. 309,039, filed of even dateherewith and entitled Parafiin Hydrocarbon Isomerization Process,describes and claims the use of adamantanoid suppressors in isomerizingparaffins by means of catalyst systems comprising a combination of AlClwith partially dehydrated adsorbents of certain types such as alumina.

BACKGROUND OF THE INVENTION This invention relates to the isomerizationof paraffinic feedstocks by means of an aluminum chloride catalyst atrelatively low temperatures. The invention is particularly concernedwith the isomerization of parafllns under conditions that provide goodisomerization rates while minimizing undesirable side reactions.

There are many disclosures in the prior art relating to the use ofaluminum halide catalysts for isomerizing paraffins. The catalystusually has been used in the form of a preformed aluminum chlorideliquid complex which contains excess aluminum chloride dissolved orsuspended therein. The liquid complex is contacted with the parafiinicfeed as a separate liquid phase to effect isomerization. The effectivecatalytic component in such case is the excess aluminum chloride in thecomplex. However there are also numerous references that teachisomerization by means of aluminum halide catalysts in solid form, suchas aluminum chloride powder or a combination of aluminum chloride and acarrier'material such as alumina.

The main problem in utilizing aluminum chloride catalysts for paraflinisomerizations is to avoid side reactions involving cracking anddisproportionation. These reactions tend to destroy the catalyticcomponent due to reaction of the resulting olefinic fragments withaluminum chloride, thereby causing the formation of a complex or sludgewhich itself is not catalytically active. Besides deactivating thecatalyst these reactions reduce the selectivity of the reaction forproducing the desired isomerizate product.

In order to suppress side reactions during the aluminum halideisomerization of paraffins the use of naphthenes as suppressors has beenproposed in numerous prior art references including the following UnitedStates patents:

Patent No. Patentee Issue date 2,413,691 C. C. Crawford et al Jan. 7,1947. 2,434,437 E. Ross Jan. 13, 1948 2,438,421 E. E. Sensel et al Mar.23, 1948 2,468,746 B. S. Greensfelder at May 3, 1949 2,475,358.. R. J.Moore et a1 2,992,285 F. W. Arey, Jr., et al July 11, 1961 3,280,213 G.C. Mullen, Jr., et al Oct. 18, 3,285,990-". I. '1. Kelly et a1 Nov. 15,1966. 3,557,479 D. E. Jost. et a1 May 4, 1971. 3,578,725 D. E. Jost atal May 11, 1971.

The use of naphthenes for this purpose is also discussed by Condon inCatalysis, Vol. 6 (1958), pages 82-98, Reinhold Publishing Corp., and inan article by Evering et al. in Ind. Eng. Chem., 45, No. 3, pages582-589 (1953). While naphthenes in the reaction mixtures will suppressundesirable side reactions at relatively low temperatures, they alsotend to suppress the isomerization rates. If the temperature isincreased to expedite the isomerization reaction, the naphthenesthemselves then become reactive and form carbonium ions. The latter cancause the parafiin feed to undergo deleterious side reactions. Thenaphthenic ions also can convert, through loss of protons, to olefinicproducts which will react with the aluminum chloride to form sludge anddestroy the catalyst.

When the paratfinic feed is of the C -C range, naphthenes can besatisfactorily used as suppressors inasmuch as the pentanes and hexanesare not especially prone to undergo cracking and disproportionationreactions. However, when the feed is of the C and higher range, or evenwhen it is mainly of the C 43 range but contains minor amounts of O,and/or higher parafiins, the use of naphthenes has not provided asatisfactory solution to the side reaction problem, as these higherparatlins are much more prone to crack and/or disproportionate underconditions that otherwise would provide a reasonable isomerization rate.This circumstance was pointed out by Pines et al., Adv. in Pet. Chem.,and Ref., III (1960), page 154, and is still applicable to the priorart. Therein the authors state: Isomerizing heptanes and higherparaffins has met with little practical success [citations]. Althoughsome isomerization occurs, the bulk of reaction is cracking. Inhibitorseffective for pentane and hexane isomerization appear to have littleeffect with the higher alkanes.

Pat. 2,438,421, cited above, is exemplary of the use of monocyclicnaphthenes for suppressing cracking during the isomerization ofparaflins having less than seven carbon atoms. Specific examples werecarried out with n-pentane at F. (71 C.) and 200 F. (93 C.) employingpowdered AlCl together with HCl, with a reaction time of 4 hours andboth with and without a naphthene suppressor. While the data show thatthe naphthenes used were effective in suppressing cracking, they alsoshow that the isomerization reaction was quite slow and that the degreeof conversion to isopentane was low.

Examples of the isomerization of C parafiins in the presence ofmonocyclic naphthenes are given in abovecited Pats. 3,280,213 and3,285,990. The processes therein described utilize catalysts prepared byreacting an adsorbent such as alumina with AlCl at elevated temperature(ZOO-350 F.) and then with gaseous HCl at lower temperature (ISO-200F.). While the latter patent mentions heptane as a feedmaterial, nospecific example is given wherein heptane was present.

Pats. 2,468,746 and 2,475,358, also cited above, teach the use ofnaphthenes as suppressors in the isomerization of higher parafiins. InPat. 2,468,746 the feed is composed of C -C n-paraflins and the intendedisomerization product is diesel fuel, while in Pat. 2,475,358 the feedis solid parafiin wax which is isomerized to yield oil. Both patentsdisclose that the naphthene suppressor can be monocyclic, dicyclic ortricyclic, and a number of specific examples of such naphthenes arerecited including adamantane. The patentees teach, however, that thecatalyst cannot be AlCl per se, as in the absence of suppressor it willcause extensive cracking while in the presence of sufficient suppressorto inhibit cracking the isomerization reaction will also be repressed.Consequently, the catalyst is required to be modified in the form of aliquid complex containing excess aluminum chloride. Such complexcatalyst and hydrocarbons have little mutual solubility and hence wouldconstitute separate phases within the reaction zone. In order forreaction to occur the hydrocarbon reactant has to diffuse into theliquid complex phase and to the sites of excess aluminum chloridetherein, which diffuion necessarily would occur slowly due to the lowsolubility of paraffin hydrocarbons in the complex. Furthermore, afterreaction at the catalyst site has occurred, the resulting isomericparafiin has to diffuse out of the complex phase to the hydrocarbonphase. The rate of the isomerization reaction is thus limited by masstransfer between the phases. This means that in order to securereasonable reaction rates intimate mixing of the phases would berequired, which necessarily would entail high power costs.

SUMMARY OF THE INVENTION The present invention provides an improvedmanner of isomerizing paraffinic hydrocarbons, which is applicable toparaffins ranging from pentane to and including paraffin waxes, andhydrogenated polyethylene. The invention is based on the discovery that,among the many hydrocarbons broadly classifiable as naphthenes,adamantanoid hydrocarbons are unique in their ability to function assuppressors of side reactions during the isomerization. By employing anadamantanoid hydrocarbon suppressor together with a halohydrocarbonpromoter as hereinafter described, it has been found that parafiins canbe isomerized at good rates by means of powdered AlCl as catalyst andwith minimal amounts of side reactions.

According to the invention, paraffin hydrocarbons are isomerized bymeans of solid aluminum chloride catalyst in a process which comprises:

(a) contacting a parafiinic feed substantially free of unsaturatedhydrocarbons and having at least five carbon atoms per molecule inliquid phase with AlCl in the form of particulate solid at a temperaturein the range of -20 to 130 C. and in the presence of a minor amount ofsaturated halohydrocarbon promoter in which the halogen is chlorine orbromine and also in the presence of a suppressor comprising adamantanoidhydrocarbon selected from the group consisting of adamantane, C Calkyladamantanes having 1-3 alkyl substituents, diamantane and C -Cmonoalkyldiamantane in which the alkyl substituent is attached at abridgehead position through a primary carbon atom;

(b) continuing said contacting until substantial isomerization of theparaffinic feed has occurred;

(c) and recovering a parafiinic isomerizate from the reaction mixture.

DESCRIPTION The adamantanoid hydrocarbons employed as suppressors in thepresent invention include adamantane (C alkyladamantanes (C -C whichhave 1-10 total alkyl carbon atoms constituting 1-3 alkyl substituents,diamantane (C and monoalkyldiamantanes (C -C in which the alkylsubstituent has 1-10 carbon atoms and is attached through a primarycarbon atom to a bridgehead position of the nucleus. The nuclei ofadamantane and diamantane can be depicted as follows:

adaman tarie diamantane As can be seen the adamantane nucleus containsthree condensed rings with four bridgehead carbon atoms which aretertiary and equivalent to each other and which are separated from eachother by a secondary carbon atom. Diamantane comprises two condensedadamantane nuclei. Unlike the ring systems of non-adamantanoidnaphthenes, these structures are unique in that they are incapable offorming an olefinic bond by removal of hydrogen [this being inaccordance with Bredts rule-see Mechanism and Structure of OrganicChemistry by Gould (1959), page 348]. The adamantanoid suppressorsspecified above therefore cannot, in distinction from other kinds ofnaphthenes, convert under the reaction conditions to olefinic productsthat can deactivate the aluminum chloride catalyst.

Methods of preparing the adamantanoid hydrocarbons above specified areknown in the art. The preparation of adamantane is described, forexample, in U.S. Pat. 3,274,- 274, H. E. Cupery, issued Sept. 20, 1966;and U.S. Pat. 3,489,817, E. C. Capaldi et al., issued Jan. 13, 1970.Numerous references describe the preparation of alkyladamantanes; see,for example, U.S. Pat. 3,128,316, A. Schneider, issued Apr. 7, 1964, andthe various references given in U.S. Pat. 3,646,233, R. E. Moore, issuedFeb. 29, 1972. The production of diamantane and methyldiamantane isdescribed by T. M. Gund et al., Tetrahedron Letters, No. 4, pp.3877-3880 (1970) and E. Osawa et al., J. Org. Chem., 36, No. 1, pp.205-207 (1971). Alkyldiamantanes in which the alkyl group is C -C andattached to the nucleus through a primary carbon atom can be made frombromodiamantane by a Grignard type synthesis analogous to that shown inthe last-mentioned article for making methyldiamantane.

When alkyladamantanes are used as suppressors in the process of thisinvention, the suppressor can have one, two or three alkyl substituentson the adamantane nucleus, and it is immaterial whether the substituentsare located at bridgehead or non-bridgehead positions or both.

The present process is applicable to a wide range of paraffinic feedsranging from n-pentane through the gasoline and lubricating oil boilingranges and including normally solid parafiinic materials such asparaffin waxes and hydrogenated olyethylenes. The feed should besufiiciently free of aromatic and olefinic components so thatsubstantial complexing of the catalyst with such unsaturated componentswill not occur. The feed can contain monocyclic and dicyclic naphthenesnormally associated with the feed paraffins but preferably the contentthereof does not exceed 30% by weight.

The process is carried out at a temperature in the range of 20 to C.,with temperatures of 1080 C. usually being preferred. The feed in liquidphase is contacted with powdered AlC1 at the selected temperature in thepresence of an adamantanoid suppressor, as specifier above, and also inthe presence of a saturated halohydro carbon promoter as more fullydescribed hereinafter. Th, promoter is an essential element of thereaction systemv An inert halohydrocarbon solvent, e.g.1,1,2,2-tetrachloroethane, can be used in the mixture, but such solventis essential only when the paraffin feed is normally a solid material atthe selected reaction temperature. However the use of an inert solventcan be beneficial also when the feed is normally liquid, since it willhelp to keep the AlCl catalyst surfaces clean by dissolving any traceamount of catalyst complex that may form and thereby prevent blocking ofactive catalyst sites. Even without a halohydrocarbon solvent present,however, there is little tendency for the catalyst to form sludge andbecome deactivated. The presence of the adamantanoid hydrocarbon in thereaction mixture tends to prevent this by immediately combining with anyolefinic fragments that may form in small amounts due to side reactions,thus preventing their reaction with the aluminum chloride.

After the liquid phase has been contacted with the powdered AlCl longenough to achieve the desired degree of isomerization, contacting isdiscontinued and the AlCl is separated from the bulk of the liquid as byfiltration or decantation. Substantially no loss in activity of thecatalyst is experienced and the catalyst generally is recovered in cleanform without discoloration, indicating the absence of complex. Thecatalyst can be recycled to the isomerization zone for further use. Theliquid phase is distilled to separate the paraffinic isomerizate fromthe adamantanoid material, and from solvent whenever same has been used,and the adamantanoid hydrocarbon and solvent can also be recycled to theisomerization zone for further use.

As a specific illustration of the invention, a blend of n-pentane (2.0ml.), 1,1,2,2-tetrachloroethane (2.0 ml.) as solvent,1,3-dimethyladamantane (1.0 ml.) as suppressor and cyclohexylbromide (25microliters) as promoter is prepared and is shaken at 50 C. withpowdered AlCl (1.0 g.) for one hour. This results in the isomerizationof the n-pentane to the extent of approximately 60%, without anycracking or disproportionation taking place. No complexing of thecatalyst occurs, as indicated by the fact that it remains colorless.During the reaction the bromide moiety of the promoter partly convertsto HBr and is partly incorporated through halogen exchange into thealuminum halide. The cyclohexyl group converts to a mixture ofcyclohexane and methylcyclopentane.

For convenience hereinafter DMA is used to designate1,3-dimethyladamantane and TCE denotes 1,1,2,2- tetrachloroethane.

As another specific illustration, a blend of n-nonane (1.01 ml.), DMA(2.0 ml.) as suppressor, TCE (2.0 ml.) as solvent and1-bromo-3,S-dimethyladamantane microliters) as promoter is saturatedwith dry HCl and the mixture is shaken with powered AlCl (1.0 g.) at 26C. for 30 minutes. This results in the conversion of about 60% of then-nonane to a mixture of branched nonanes and of about 10% to C Cparafiins. The catalyst remains clean and colorless. The composition ofthe nonane portion of the product is about 25% doubly branched Cparaffins, 35% singly branched C paraffins and 40% n-nonane.

The use of a halohydrocarbon promoter is, as above indicated, anessential feature of the process, although the proportion of promoterrequired in the reaction mixture is small. The promoter can be anysaturated chlorohydrocarbon or bromohydrocarbon which is capable ofinterchanging halogen for a bridgehead hydrogen of the adamantanoidsuppressor in the reaction system. When the halohydrocarbon promoter andthe adamantanoid suppressor are brought together in the presence of theAlCl such interchange occurs and the resulting haloadamantanoid compoundbecomes the promoter. Saturated halohydrocarbons which will serve aspromoters can be either aliphatic or cycloaliphatic. As a general rule,they have one or more chloro and/or bromo substituents and have at leasttwo carbon atoms with at least one of them having a single halidesubstituent. Exceptions to this definition are chloroform, carbontetrachloride and their bromine, analogues which also will function aspromoters. Examples of other compounds which will serve as promoters arethe following in which the halogen is chlorine or bromine or both:monohaloethane; 1,2- dihaloethane; 1,2,2,2-tetrahaloethane;1,3-dihalopropane; 1,2,3,3-tetrahal0propane;1,2,2,3,3,3-hexahalopropane; n-

or secor t-butyl halide; monohalodecanes; cyclohexyl halide; 1,3-dihalo1 methylcyclopentane; monohalodecalins; monohalonorbornanes;perhydroanthracyl halides; haloadamantanes; halodimethyladamantanes;halodiamantanes; etc.

Various chloroalkanes which in pure form are substantially inert andcannot function as promoters but which can be employed as solvents inthe isomerization system are as follows: methyl chloride; methylenechloride; 1,1,2,2-tetrachloroethane (TCE); pentachloroethane (except atelevated temperatures such as 75 C. or higher); and hexachloroethane.The use of such inert solvents in isomerizations effected by means ofaluminum halide catalysts is described in Jost et al. Pats. 3,577,479and 3,578,725 listed above.

Secondary alkyl chlorides are the preferred promoters for use in thesystem. Examples are isopropyl chloride, 2-chlorobutane and 2- or3-chloropentane. Primary halides, such as l-chloropropane,l-chlorobutane and particularly chloroethane, are less active andpreferably are not employed unless reaction temperatures aresufficiently high (e.g. above 25-40 C.). Tertiary halides, such ast-butyl chloride, preferably are used only at low temperatures (e.g. -20to 10 C.) because they otherwise are so active that they tend to form acomplex with the catalyst.

The amount of promoter employed in the reaction mixture is relativelysmall. The proportion of promoter relative to the parafiin feedcomponent is generally in the range of 0.0110.0% by volume and typicallyin the range of 01-50%. In initiating the reaction the promoterinterchanges a halogen atom for a bridgehead hydrogen atom of theadamantanoid suppressor. Thus isopropyl chloride becomes propane, and2-hexyl chloride converts to hexane which thereafter will isomerize tobranched hexanes while the feed paraffin is being isomerized.

The proportion of the adamantanoid suppressor to paraffin in thereaction mixture can vary Widely. Benefits from the presence of thesuppressor can be noted, for example, with volume ratios of suppressorto parafiin ranging from 3:97 to 90:10. Optimum proportion ranges willvary depending upon the particular paraffinic components of the feed andmay also to some extent depending upon the particular adamantanoidhydrocarbon employed as suppressor. Optimum proportions usually fallwithin the ranges of 20:80 to :20 if the feed contains no naphthenes and7:93 to 80:20 when such naphthenes are present. By way of example, goodresults are obtainable for C -C parafiinic feed containing no naphthenesat suppressor:paraffin ratios by volume of 20:80 to 50:50, for Cparafiin at 50:50 to 75:25, and for C and higher paraffins at 60:40 to80:20. Some of the adamantanoid suppressors, e.g. adamantane, diamantaneand their mono methyl derivatives, are normally solid compounds attemperatures suitable for the isomerization. However they havesubstantial solubilities in liquid paraffinic feeds and are generallyusable as suppressors even when no inert solvent is employed in thereaction mixture. In cases where it is desired to utilize suppressor toparaffin ratios higher than that corresponding to the solubility ofsuppressor in the feed at the selected reaction temperature, an inerthalohydrocarbon solvent, as previously specified, can be employed toinsure solubilization of the suppressor in the amount desired.

For feedstocks containing C or higher paraffins it is beneficial tocarry out the reaction in the presence of hydrogen chloride or hydrogenor both. This is particularly so for C and higher parafiins which tendto crack readily. On the other hand, for C C paraffins, which are notprone to crack, little if any benefit is obtained from the use of HCl orH When cracking does occur to produce olefinic fragments, the presenceof HCl and/ or H in the reaction zone is beneficial in that the olefinicmaterial tends to react with the HCl or H or both, and thisadvantageously prevents it from alkylating the adamantanoid suppressor.Reaction of the olefin with HCl produces alkyl chloride which functionsas additional promoter for the isomerization reaction. Reaction with Hresults in the formation of saturate hydrocarbon product that boilsbelow the feed paraffin. In either case alkylation of the suppressor bythe olefinic fragments is avoided to the extent that these reactionswith HCl or H occur. The amount of HCl used can vary widely, the partialpressure thereof in the reaction zone being, for example, in the rangeof 0.01-100 p.s.i. Hydrogen can be used typically at partial pressuresin the range of 20-500 p.s.i., but optimum results usually are obtainedin the range of l300 p.s.i. If too much hydrogen pressure is employed,the isomerization rate of the feed paraffin will become undesirablyslow.

The adamantanoid material recovered from the reaction mixture can, aspreviously indicated, be recycled to the reaction zone to serve as thesuppressor in isomerizing further quantities of feed paraffin. However,since some minor amount of alkylation of the adamantanoid suppressor byolefinic fragments generally occurs, this material may upon continualuse eventually become too highly alkylated to function adequately assuppressor of side reactions. It is therefore desirable to providedistillation means for separating the lower boiling adamantanoidhydrocarbons from the more highly alkylated adamantanoid compounds sothat only the former can be recycled. If desired the more highlyalkylated compounds can be cracked at 300450 C. in the presence of aconventional cracking catalyst, such as silica-alumina or crystallinezeolites, to remove C and higher alkyl substituents in the form ofolefins and yield lower adamantanoid hydrocarbons which can be recycled.Such cracking procedure is described in U.S. Pat. No. 3,707,576, issuedDec. 26, 1972, to R. E. Moore. Alternatively the more highly alkylatedcompounds can be catalytically hydrocracked under a hydrogen pressureand other conditions as described in US. Pat. 3,489,817 cited above toyield lower adamantanoid hydrocarbons for reuse. Inasmuch as minorlosses of adamantanoid material normally will occur in practicing theprocess, a supply of the adamantanoid suppressor should be provided tomake up for any loss incurred.

Utilization of the present process for isomerizing C paraflinic stocksto produce isoparaffin components for gasoline provides an unexpectedbenefit. It has been found that the content of 2,2-dimethylbutane(2,2-DMB) in the C isomerizate product is substantially higher, and thecontent of singly branched hexanes correspondingly lower, than for Cisomerizates produced by Friedel-Crafts catalysis to the same percentconversion but in the absence of an adamantanoid suppressor. This isshown, for example, by comparison of the 2,2-DMB content-percentconversion relationship obtained by the present process with thatpublished by Brouwer et al., Div. of Pet. Chem., Am. Chem. Soc., SanFrancisco Meeting, Ap. 2-5, 1968, pp. 184-192, for a procedure in whichn-hexane in the presence of a monocyclic naphthene (methylcyclopentane)and H was isomerized by means of HF-SbF as catalyst at 50 C. Incomparison with the reported results, isomerization of n-hexane at thesame temperature but employing powdered AlCl in combination with apromoter and DMA as suppressor gives materially higher 2,2- DMB contentsat equivalent conversions. The C isomerizate of the present processaccordingly has better antiknock quality.

The present process can be utilized for making isoparafiinic gasolinecomponents from saturated feeds of the C -C range containing one or moren-paraffin components. It is especially useful for isomerizing feeds ofthe C -C range containing one or more straight chain and/or singlybranched paraffins and particularly those containing at least some C orhigher parafiins which ordinarily are highly prone to crack in thepresence of Friedel-Crafts catalysts.

Various experimental runs performed with a number of parafiin feeds (Cto C to demonstrate the invention are given below. These runs werecarried out by shaking a mixture of the paraffin, suppressor, promoter,solvent (when used) and powdered AlCl in a stoppered bottle or rockerbomb at regulated temperatures and for selected reaction times. In theseruns DMA was used as the suppressor and the solvent (when used) was TCE.In most cases isopropyl chloride was employed as the promoter. However,in runs Where TCE was used, this solvent contained a small amount ofchloroalkane impurity, not specifically identified but thought probablyto be 1,2,3-trichloropropane, which functioned as promoter. The amountof this promoter in the solvent was equivalent in promoting effect to1.35 microliters of isopropyl chloride per ml. of solvent. Consequently,in some runs no additional promoter Was added and the solvent impurityserved as the promoter. Samples of the hydrocarbon phase of the reactionmixture were taken at various times and analyzed by GLC. Results areshown in the accompanying tables.

TABLE I: RUN 1 Isomerization of normal hexane Reaction mixture:

2.0 ml. n-hexane 2.0 ml. TCE (solvent) 1.0 ml. DMA (suppressor) 50microliters n-propyl Cl 0.70 g. AlCl Total reaction time, min 0 200 320Temp, C 0 10 10 Composition, wt. percent:

C3 Trace 0.7 0. 6 F04. 0. 4: 0. 6

7. 3 11. 0 13. J 40. 6 15. 2 0. 1 (l. 1 0. 2 Cu 0. 7 0. 9 Conversion ofn-Cu, Wt. percent 20. 4 58. 7 C4-C5 products, wt. percent of n-Ce 1'0 0.3 2. 8 2,2-DMB, wt. percent of Cu products. 2. 6 22. 5

1 Nil.

The data of Table I (Run 1) show that at 10 C. the isomerization ofn-hexane in the presence of DMA and promoter proceeded, that only asmall amount of side reactions occurred, and that the usual harmfuleffects of olefinic fragments were avoided due to their capture by theDMA suppressor through alkylation forming C to C -substituted DMAs insmall amounts. No deterioration of the AlCl by complex formation tookplace, as shown by the fact that no discoloration occurred. The lighthydrocarbon products formed (C C were all paraffins. A total conversionof 58.7% was reached, at which point the 2,2-DMB content of the Cfraction was 22.5%. By Way of comparison, Brouwer et a1. (citationabove) at the same conversion level obtained only about 10% 2,2- DMB inisomerizing n-hexane at 25 C. with HF-SbF In further comparison, if Run1 is repeated except that in place of DMA a non-adamantanoid naphthene,e.g. methylcyclohexane, is employed in the same amount, the reaction isso suppressed that substantially no isomerization occurs.

TABLE II: RUN 2 Isomerization of normal heptane TABLE III: RUN 3Isomerization of 50:50 n-hexane and n-heptane Reaction mixture:

0.5 m1. n-hexane l 0.5 ml. n-heptane Reaction mixture: 2.0 m1. TOE

1.0 m1. n-heptane 2.0 ml. D M.A 4.0 m1. TOE (solvent) nncrohtersi-propyl chloride 2.0 ml. DMA (suppressor) 3.4 g. A1013 Total reactlontime, min 0 60 120 180 304 Total reaction time, min 0 66 166 188 248Temp, 25 25 25 25 1o Composition, wt. percent: Temp., 0 20 20 20 2003."... 0.22 0.21 0.21 0.21 Composition, wt. percent: 0.04 0.06 0.10Trace Trace 0.04 0.10 0.20 0.28 0. 01 1.18 1.70 2.58 0.01 0. 02 0.032.34 2.90 3.23 3.34

i-C0-. Trace 0.02 5.14 4.18 3. 03 2.10

Dimethylpentanes 1.70 2.52 3.37 3.84

Methylhexanes 5.30 5.95 0. 03 5. 30 Dlmethylpentanes 2 1.10 1.11 1. 74.2.18

11-0 4.90 2.88 1.77 1.15 Methylhexanes 3. 37 4.10 4.04 4.00

Solvent 65.9 66.6 66.5 66.9 n-Heptane 4.62 3. 39 2.59 1.75

21.7 21.7 21.7 21.2 Solvent 49.8 49.8 49.0 49.5

Cz-DMA 0.12 0.24 0.34 0.55 DMA. 32.4 32.2 32.5 32.7

C1-DMA 0.24 0.10 0. 00 0.11 Cs-DMA 0.12 0.17 0.23 Conversion of n-C wt.percent 59. 3 76. 4 85. 5 89. 8 CaDMA 0.12 0. 21 0.23 0. 23 C4-C0products, wt. percent of C1-D MA 0.24 0.35 0.35 0.45

n-C feed 0.4 0.9 1.8 2.7 Conversion of n-Cu, wt. percent. 40.8 51.8 64.6 75.8 Conversion of n-C wt. percent 48.3 62.1 71.0 80.4 2,2-DMB, wt.percent of 00 products. 7.5 14.2 21.3 32.2

1 Contained 5.6% methylcyclopentane (MOP) as impurity. 25 9 Probablyincluded cyclohexane.

Table II Shows that DMA at a PP e F 1 The data in Table III show thatn-hexane and n-heptane llme who of 211 Was e y e Y suppfessfng inadmixture with each other can be isomerized simulundesirable sidereactions while permitting isomerrzatron taneously i the presence of DMAwith only relatively of n-heptane to occur to a high conversion level.The 10W small amounts of side reaction products being formed. No amountsof C -C paraflins formed and the absence of complexing of the catalystoccurred during this reaction C and C -substituted DMAs indicate thatdisproportionaand the recovered AlCl was essentially unchanged. The tionreactions were practically entirely suppressed. In this C ntent of2,2-DMB in the C fraction of the product was run the promoter was thechloroalkane impurity in the 32.2% at 75.8% conversion of n-hexane. Incomparison solvent, the proportion thereof to n-heptane feed being theContent Shown by Brow/er et at the equivalent to 5.4 microliters ofi-propyl chloride per 1111. Same eonverslon level was y about 1 for theHF- SbF catalyst at 25 C. 4.0

TABLE IV: RUN 4 Isomerization of normal undecane TABLE II.-A: OOMPARATIVE RUN 2A Reaction mixture: Isomerlzatlon of normal heptane withmethylcyclohexane as suppressor 0.5 ml. mundecane (Cu) Reaction mixture:-0 1111- DM 1.0 m1. n-heptane 2.0 m1. TOE TOtE (lsolvlerlilt) (MCH) 0.85g. A1013 8 8.119 22 iff y We X Total reaction time, min. 0 103 223. 253

' mi 0 00 183 emn. C 0 20 20 Total reaction time, n Con-position wt.percent: Temp., 0 24 24 1-0 0.10 0.29 Composition, wt. percent: 0.360.53

Methylhexane 0.1 t 0.28 0.60

n-Heptane 12.0 12.2 11.4 1-C1 0.51 0. 73

MCH 23.9 21.0 22.7 lv n 50.0 58.7

Solvent 04.1 00. 0 05.2 Doubly branched (311-- 1.5 1. 8

Single branched C11. 2. 0 1. 6 n-Undecane... 2. 5 1. 6

DMA 34.5 33.9 32.9 Gl-DMA 0.08 1.10

Cls-DMA 0.55 0.82 Cfl-DMA 0.80 1.14 G1-DMA 0.53 0.79 ou-pMA 0.27 0.53Conversion of 11-011, wt. percent 76. 8 84. 8 C4-C1 products, wt.percent of n-Cn feed 12.4 20. 3

The conditions of Run 2-A were a substantial duplica- 1 N9 changetion ofthose used in Run 2 except that MCH was used as the suppressor in placeof DMA. The data in Table II-A show that the isomerization reaction wasalmost entirely o zfi If z f? 3 W i s S The results in Table IV showthat the isomerization of e e ey o l l ph t g W011 arge Y e C parafiinto high conversions can be effected in the isomerlz tl nt e 1 hand, IfIt were ralsed Sllf presence of the adamantanoid suppressor withoutexcesficlenfly eallse lsomellzatlon to Proceed at reasonable sive sidereactions. While substantial amounts of C -C f the M wollld e be Capablef pp g efeekproducts were formed, the catalyst remained unaffected mg ad dISPIOPOIIIOHaUOII, and ea tion of olefinic prOdand no discolorationof the mixture occurred. In Run 4 note with the AlC1 would occur,destroying the catalyst. as in Run 2, the promoter was the chloroalkaneimpurity in the solvent, the proportion thereof to paraffin being thesame as in Run 2.

TABLE V: RUN 5 Isomerization of normal oetadecane The data in Table Villustrate the fact that normally solid paraffins can be successfullyisomerized to high conversion levels in the presence of an adamantanoidsuppressor and without inordinately high proportions of crack- R ti aggfji gfi (C18) 5 mg products being made. In other words solid paratfins3-8 can be converted in good yields to saturated lubricating A10], oilsin this manner. In Run 5 the promoter again was sup- Y H91 (toSaturation and 1 atmos- D plied by the chcloroalkane impurity in the TCEsolvent. T0m1ma i n im ,min 0 12 26 152 Table VI presents four runs onisomerizing n-heptane Temp 0 C 26 26 0 1n the presence of DMA. In Runs 6and 7 no chloroalc m o'sitiohfiifl'flifii} kane promoter was employed,while in Runs 8 and 9 iso- 1 propyl chloride was utilized as promoter.In Run 7 the 1-C5. Trace 0.20 0.34 i-c. 0.16 0.23 reactlon mixture wasinitially Saturated with dry HCl.

8' 8-?8 The data in Table VI show that the presence of a proi-Co. 2 1082 0; motor is necessary for the isomerization to proceed at $121 53 3 223 1 5 1 suitable rates. Run 7 shows that HCl per se will not funcfi g 173-32 gg tion as promoter. Run 8 shows that with a chloroalkane C;-DMA:11:11:11: 0124 0:46 promoter present an inert chlorohydrocarbon solventis Triply branched C15. 0.26 1.71 2.05 Doubly branched Cm" L51 284 2.56not essential fol practicing the invention. Run 9 shows singly branched1s- 8. 1% 3- 2; 28 that n-heptane can be isomerized to high conversionlevels 11- 1s Conversion omen, 335 yfh present P s Wlthout excesslveamounts of lower 4 v p percent of 11-015 0 6 4 9 6 boiling productsbeing formed. In all of these runs no Ge l discoloration ordeterioration of the catalyst occurred. 1 Nil.

TABLE VI: RUNS 6-9 Isornerization of n-heptane in presence of DMA Run 6Run 7 Run8 Run9 Solvent (TCE) used No No No Yes M1. TCE/m1. ofn-C 4Promoter used None None i-Propyl Cl i-Propyl Cl Mieroliters/inl. of n-C110 20 1101 used No Yes* No No Wt. ratio of DMAm-Cv. 64:36 64:36 65:3551:49 G. AlOla/ml. 01 11-01. 0. 33 0. 31 0.98 0. 94 Total reaction time,hrs 1. 0 3.0 1. 0 1. 0 3.0 0. 5 1 Temp., C 50 25 26 26 24 24 Conversionof 11-01, Wt.

091 0.5 2.2 0 33.4 59.8 71.5 84.4 C4-C1 products, wt. percent of n- 1 ed0 0 0 Trace 0.6 3.1 7.2

" Reaction mixture saturated with dry HCl at 1 atmos. press. and 25 C.

TABLE VII: RUNS 10-14 Isom erization of n-oetane at various H2 pressuresReaction mixture:

1.0 ml. n-oetane (11.8 wt. percent of organic phase) 2.0 ml. DMA 4.0 m1.TCE AiCla and HCl (as listed) Reaction temp: 26 0.

Run 10 Run 11 Run 12 Run 13 Run 14 G. A1013 1.12 0.89 0.89 1.00 0.01 Hzpartial press, p.s.i 0 100 193 201 298 H01 partial press, p.s. 10 10 1010 Total reaction time, min 120 240 120 Composition, wt. percent:

C C paraffins 1.82 2.87 2.01 0.23 2.63 Trace Dimethylhexanes 2.51 1.042.81 1.21 3.13 0.27 Methylheptanes 3.34 1.66 2.01 3.31 3.41 1.87 11-032.05 0.65 1.63 7.00 2.07 10.10 67.5 68.3 67.4 66.5 63.8 65.0 DMA....10.4 17.5 20.0 21.3 20.0 21.8 Alkylated DMAs 1.41 5. 08 2.35 1.06Conversion of n-Ca, wt. percent 74. 8 94. 5 86. 2 40. 1 82. 4 14. 1C4-C1 parafiins, wt. percent n-Ca feed" 15.4 24.4 24.7 2.0 22.3Isooctenes, wt. percent of nCa feed 49. 7 30. 5 48. 6 38.4 55.5 18. 2Consumption of H2, A p s i 2.5 1 1 Relaction mixture saturated with HCIat 0 C. and 1 atmos. press.

Table VII presents data from comparative runs on isomerizing n-octane at26 C. at various H partial pressures ranging from to about 300 p.s.i.The results show that the use of hydrogen pressure in the reaction zonecan be beneficial and indicate that optimum results for reaction at 26C. are obtained at a hydrogen partial pressure in the neighborhood of200 p.s.i. The elfect of the hydrogen is to allow the conversion ofn-octane to be carried further without excessive alkylation of theadamantanoid suppressor, whereby higher yields of isooctanes and highercontents of doubly branched C hydrocarbons in the isooctane fraction canbe secured. Run 14 shows that at 265 C. a partial pressure of H as highas about 300 p.s.i. retards the reaction rate too greatly; but thiscould be compensated for by raising the temperature level and stillsecuring benefits from the presence Of H2.

When other adamantanoid hydrocarbons as herein specified are used inplace of DMA as suppressor, substantially similar results are obtainedalthough some differences in suppressing action may be noted fordiiferent adamantanoid compounds. The degree of suppression under agiven set of reaction conditions generally tends to decrease as thedegree of alkylation of the adamantanoid nucleus increases. Thusadamantane and diamantane usually exhibit the strongest suppressingactions, so that lower amounts of these in solution generally will exertequivalent suppressing actions to higher amounts of alkyladamantanes.However, for convenience in material handling in the present process, itcan be preferable to employ a normally liquid suppressor, such as DMA,rather than one that is normally solid such as adamantane and diamantaneand to utilize a somewhat larger proportion of the normally liquidsuppressor in order to obtain an equivalent suppressing action.Suppressors generally preferred are the C -C alkyladamantanes having 1-3alkyl substituents of the C -C range, examples being methyladamantane,dimethyladamantane, ethyladamant ane, ethylmethyladamantane,trimethyladamantane, ethyldimethyladamantane and mixture of two or moreof same.

When other non-inert saturated chlorohydrocarbons or bromohydrocarbons,as previously described, are used in place of the alkyl chlorides shownin the foregoing examples as promoters, substantially analogous resultsare obtained. It is generally preferable, however, to use achlorohydrocarbon rather than a bromohydrocarbon in order to avoid abromine-chlorine interchange reaction with the powdered AlCl Theinvention claimed is:

1. Process for isomerizing parafiins by means of solid aluminum chloridecatalyst Which comprises:

(a) contacting a parafiinic feed substantially free of unsaturatedhydrocarbons and having at least five carbon atoms per molecule inliquid phase with AlCl in the form of particulate solid at a temperaturein the range of -20 to 130 C. and in the presence of a minor amount ofsaturated halohydrocarbon promoter in which the halogen is chlorine orbromine and also in the presence of a suppressor comprising adamantanoidhydrocarbon selected from the group consisting of adamantane, C -Calkyladamantanes having 1-3 alkyl substituents, diamantane and C -Cmonoalkyldiamantane in which the alkyl substituent is attached at abridgehead position through a primary carbon atom said promoter beingcapable of interchanging said halogen for a bridgehead hydrogen of saidsuppressor;

(b) continuing said contacting until substantial isomerization of theparafiinic feed has occurred;

(0) and recovering a paraflinic isomerizate from the reaction mixture.

2. Process according to Claim 1 wherein said suppressor is adamantane.

3. Process according to Claim 2 wherein said promoter is a secondaryalkyl chloride.

4. Process according to Claim 1 wherein said feed comprises n-parafiinof the C -C range.

5. Process according to Claim 4 wherein said promoter is a saturatedhydrocarbyl chloride and said temperature is in the range of 1080 C.

6. Process according to Claim '1 wherein said promoter is a chloroalkaneor a bridgehead chloride of said adamantanoid hydrocarbon.

7. Process according to Claim 6 wherein said promoter is a secondaryalkyl chloride.

8. Process according to Claim 1 wherein said feed is of the C -C rangeand comprises n-heptane.

9. Process according to Claim 1 wherein said feed contains a C or higherparafiin and said contacting is effected in the presence of H at apartial pressure below 500 p.s.i.

10. Process according to Claim 9 wherein the H partial pressure is inthe range of -300 p.s.i.

11. Process for isomerizing parafiins by means of solid aluminumchloride catalyst which comprises:

(a) contacting a paraffinic feed substantially free of unsaturatedhydrocarbons and having at least five carbon atoms per molecule inliquid phase with AlCl in the form of particulate solid at a temperaturein the range of -20 to C. and in the presence of a minor amount ofsaturated halohydrocarbon promoter in which the halogen is chlorine orbromine and also in the presence of a suppressor comprising adamantanoidhydrocarbon selected from the group consisting of C C alkyladamantaneshaving 1-3 alkyl substituents, diamantane and C -C monoalkyldiamantanein which the alkyl substituent is attached at a bridgehead positionthrough a primary carbon atoms;

(b) continuing said contacting until substantial isomerization of theparafiinic feed has occurred;

(c) and recovering a paraflinic isomerizate from the reaction mixture.

12. Process according to Claim 11 wherein said suppressor is C -Calkyladamantane having 1-3 alkyl substituents of the C -C range.

'13. Process according to Claim 12 wherein said suppressor isdimethyladamantane.

14. Process according to Claim 12 wherein said promoter is a secondaryalkyl chloride.

15. Process according to Claim 11 wherein said suppressor is G -Cal-kyladamantane having 1-3 alkyl substituents of the C -C range, saidpromoter is a saturated hydrocarbyl chloride and said temperature is inthe range of l080 C. and said feed comprises n-parafiin of the C Crange.

16. Process according to Claim 9 wherein said suppressor isdimethyladamantane.

17. Process according to Claim 11 wherein said feed mainly comprises oneor more paraffins of the C -C range which are straight chain or singlybranched, said temperature is in the range of l080 C., said promoter isa saturated hydrocarbyl chloride, and said suppressor ismethyladamantane, dimethyladamantane, ethyladamantane,ethylmethyladamantane, trimethyladamantane, ethyldimethyladamantane or amixture of two or more of same.

18. Process according to Claim 17 wherein said suppressor isdimethyladamantane.

19. Process according to Claim 11 wherein said promoter is a bridgeheadchloride of a C -C alkyladamantane.

20. Process for isomerizing C paraflin hydrocarbons which comprises:

(a) establishing a hydrocarbon mixture substantially free of unsaturatedhydrocarbons and containing essentially (1) C paraffin having less thantwo branches and -(2) an adamantanoid hydrocarbon tane in which thealkyl substituent is attached at a bridgehead position through a primarycarbon atom,

the volume ratio of said adamantanoid hydrocarbon suppressor to Cparaflin being in the range of 3597 to 90: 10;

(b) contacting said mixture under isomerizing conditions with a solidaluminum chloride catalyst at a temperature in the range of --20 to 130C. in the (b) contacting said mixture under isomerizing conditions witha solid aluminum chloride catalyst at a 10 temperature in the range of20 to 130 C. in the presence of a minor amount of saturatedhalohydropresence of a minor amount of saturated halohydrocarbonpromoter in which the halogen is chlorine or bromine; (c) and recoveringfrom the reaction mixture a C carbon promoter in which the halogen ischlorine or paraffinic isomerizate containing 2,2-dimethylbutane.bromine said promoter being capable of interchang- 22. Process accordingto Claim 21 wherein said volume ing said halogen for a bridgeheadhydrogen of said 5 ratio of suppressor to C paraflin is in the range of20:80

suppressor; to 80:20.

(c) and recovering from the reaction mixture a C References Citedparafiinic isomerizate containing 2,2-dimethylbutane.

21. Process for isomerizing C paraffin hydrocarbons UNITED STATESPATENTS which comprises: 20 3,523,072 8/ 1970 Schneider 260683.76

(a) establishing a hydrocarbon mixture substantially 2,475,358 7/1949Moore et al 260--683.76 free of unsaturated hydrocarbons and containinges- 2,468,746 5/1949 Gfeensfelder t al- 83- 6 sentially (1) C paraffinhaving less than two 3,671,598 6/ 1972 Moore 260-666 P branches and (2)an adamantanoid hydrocarbon suppressor selected from the groupconsisting of 25 DELBERT E. GANTZ, Primary Examiner C C alkyladamantaneshaving 1-3 alkyl substituents, diamantane and C C monoalkyldiaman-CRASANAKIS Asslstant Exammer

1. PROCESS FOR ISOMERIZING PARAFFINS BY MEANS OF SOLID ALUMINUM CHLORIDECATALYST WHICH COMPRISES: (A) CONTACTING A PARAFFINIC FED SUBSTANTIALLYFREE OF UNSATURATED HYDROCARBONS AND HAVING AT LEAST FIVE CARBON ATOMSPER MOLECULE IN LIQUID PHASE WITH ALCL3 IN THE FORM OF PARTICULATE SOLIDAT A TEMPERATURE IN THE RANGE OF -20 TO 130*C AND IN THE PRESENCE OF AMINOR AMOUNT OF SATURATED HALOHYDROCARBON PROMOTER IN WHICH THE HALOGENIS CHLORIN OR BROMINE AND ALSO IN THE PRESENCE OF A SUPPRESSORCOMPRISING ADAMANTANOID HYDROCARBON SELECTED FROM THE GROUP CONSISTINGADAMANTANE, C11-C20 ALKYLADAMANTANES HAVING 1-3 ALKYL SUBSTITUTENTS,DIAMANTRANE AND C15-C24 MONOALKYLDIAMANTANE IN WHICH THE ALKYLSUBSTITUENT IS ATTACHED AT A BRIDGEHEAD POSITION THROUGH A PRIMARYCARBON ATOM SAID PROMOTER BEING CAPABLE OF INTERCHANGING SAID HALOGENFOR A BRIDGEHEAD HYDROGEN OF SAID SUPPRESSOR; (B) CONTINUING SAIDCONTACTING UNTIL SUBSTANTIAL ISOMERIZATION OF THE PARAFFINIC FEED HASOCCURED; (C) AND RECOVERING A PARAFFINIC ISOMERIZATE FROM THE REACTIONMIXTURE.